Process of vulcanizing rubber



1 described.

1 i Patented May 3, 1932 UNITED sur s cLAYroN orrn'nonrrrnitn .wmrrnrn scorcalor ivr rno, WEST. aemihrssmmssa TO THE RUBBER, snnvrcs LABORATORIES OHIO 00., or AKRON, 01110, a CORPORATION or rnocnss or VULCANIZING RUlBIB ER Ne Drawing. Original application filed. Aprils, 192e, se'riailiv g oaeeg Divided are this a pease filed November 21, 1929. Serial to. 468,926.

he present invention is'direct'e d to the vulcanization of rubber by a process where in a new compound obtained as. hereinafter.

described and. possessi igldesirable characteristics for the use desired,fisemployed as an accelerator of the vnlcaniz at-ionprocess. The 1nvent1on .w1ll be readilynnderstood from the following specification'whereinthe.

novelty. of the" process 'is fully set forth and Various types of compounds have been described heretofore as. accelerators of the.

rubber vulcanization process. ,Among such compounds are the aldehyde-amine reaction; products. which have been developed recently. and are now widely employed for thisQ purpose. .For example, British Patent No.7,370 of 191 to Peachy, French Patent No. 470,833 to Bastideand United=States Patent No.

1,417,950 to Cadwell all disclose as,accelera- I 5 p r ion 11. butylidenegdian fasthisc tors, the use of compoundsobtained by the condensation of equi-molecular' proportions of aldehydes and amines. more recent patent to North (U. 5. Patent No, 1,467 ,984

claims as accelerators of the rubbervulcani zation process, those compounds obtainedby. treatlng the, simple. reaction. products,,.of. aldehydes and amines first formed, ;tl1at,.1s.

Schifis bases with a further. quantity. of. an

aldehyde. Tlie. process of manufacturing compounds of this type is, described and claimed in a copending application Serial No. (327,326, filed by C, North on March 24, 1923. Furthermore, the process of manu fracturing a product of this general type by reacting an aldehyde with an aminefinother than equi nolecular proportions and then re acting the product-so formed .Witha further quantity. of the same or adifierent aldehyde is claimed in another copeiiding application. a

Serial No. 627,325 filed March 24, 1923 by C. 0. North.

Aldehydes :and amines; particularly; the aliphatic aldehydes and theprimary aromatic amines, not only combine in equimole'cular proportions as Well as. in'other ratios as'are set forth inthe.applicationsv mentioned to produce reaction products but also react inthe proportion or two molecules of the amine to one molecule of an aldehyde r one m l iil e r i e 2 P r s) at.

the'mixture at a point below.35, G if 3 To the butylidene-diamlide manufacturedfi Th P ntin-Q eme 1a an. s -Wa e re the Ya continuation in partio f theone lastindicated,

file .hay'e. new ,found that a rubber v vulcanih n a el re be li an faqtured by butyric; aldehyde-dianilide or a like compound with heptal dehyde and the like in the ma in a is 119W: ees b i- Su h. j material is preferably manufactured i steps dema be ae -ly 'ebt eed byi embi i a butyric aldehyde 'with two molecular pro pla'rts otamline, I In this way nbii ation takesplace very r e adilyg and $11106 the reactionis. an, exothernncone,

the reac ing inizgturewillheat up. appreciably if the materials are all added; at th Same. time; Q For-pt his reasom it is preferable to,sup,-' ply suitablestirring mean in .the reaction vessel and also to provideinternal or external mentioned. and is 1a e 1 d e. is peer ge, ,lnasmuclr.-

heating or cooling meansito the. .ves sel in S-C 'order, to maintain ,the temperature of the i ixture uniformlyaat.,chosenpoint, Inasmuch as decomposition .of the prod: uctlor side reactionsmay (take. place if the temperaturesis allowed to become, too high, it?

it is preferable tofad d the aldehydelat such a rate that the stirring, and cooling means i Willat all times maintain, .the temperature of as abovedescribed, there isadded one molec; ular proportion (11LHparts) of heptaldee hyde. The reaction of this'second' aldehyde wit-l the dianilide takes place somewhatmore slowly. than does thefirst reactionmentioned.

and the temperature of .the mixture: is there- 1"'ore -morel .readily. controlled. However, it,

is preferable :tomaintain the temperature at alltimesbelo vy m? C. by employing the cool+ r.

ing'meansmentioned In order that the aldehyde may completely react with the dianilide, the product should be allowed to stand for a period of time, with or without stirring as desired.

After the reaction is completed, the water of condensation is drawn ofi and any residual water remaining in the reaction product is removed by drying, preferably by heating under a vacuum. The product so obtained, in the case of the substances mentioned, is a yellow, oily liquid, possessing a specific gravity of 1.080. This material, which is a heptaldehyde reaction product of butylidenedianilide, is ready for incorporation into a rubber mix in the manner as is hereinafter described. Other accelerators analogousto the one just described may be prepared in a similar manner by the use of other ingredients in place of those mentioned. Thus two molecular proportions of aniline (186 parts) are reacted and combined with one molecular proportion (45 parts) of acetaldehyde while maintaining the temperature below 30 C. The ethylidine-dianilide so obtained is then reacted with one molar proportion (114 parts) of heptaldehyde and the product maintained for some time at a temperature below '50" C. The water of condensation is then separated from the mate rial and any residual moisture is removed preferably by drying under a vacuum. The dried product is an orange yellow liquid'having a specific gravity of 1.063.

The heptaldehyde derivative of a Schifis base of the type obtained by interacting equimolecular proportions of an aldehyde and an amine may likewise be readily prepared. Thus two molecular proportions (186 parts) of aniline are reacted with two molecular proportions (140 parts) of crotonaldehyde while maintaining the mixture at temperatures below 60 C. In order to avoid overheating the mixture by the heat evolved during the reaction, it is desirable to add the aldehyde in comparatively small portions with stirring over a period of time. After the aldehyde has been all added the water of condensation may be removed if desired, although in this case, as in the other examples as shown, such intermediate drying is not absolutely necessary. The product so obtained is then further reacted in the manner already described with one-half molecular proportion (57 parts) of heptaldehyde and the resulting product dried. The product is a soft, dark red resin.

Productssimilar to those hereinbefore described may, of course, be prepared by the use of other ingredients than those particularly.

mentioned. Thus Schifis bases or aldehyde derivatives thereof prepared by the reaction of equi-molecular proportions of the amine and aldehyde, or by the reaction of two molar parts of the amine with one molar part of aldehyde or by the reaction of three mols of the aldehyde with two mols of the amine or any other proportions may be obtained by reacting together in the necessary proportions primary aromatic amines such as aniline, the toluidines, the xylidines and the like with aldehydes preferably of the aliphatic series, such as formaldehyde acetaldehyde, propionaldehyde, butyric aldehyde, heptaldehyde or with unsaturated aldehyde such as croton aldehyde, acroleinaldehyde or with substitute aldehydes such as aldol and the like. The

SchifPs bases or the aldehyde derivatives thereof so obtained are then further reacted with heptaldehyde or other aldehyde in the manner as described.

It is not, of course, necessary that heptaldehyde be used only to produce the final reaction product. An amine may be reacted first with heptaldehyde to produce a Schiffs base and this product may then be further reacted with butyric aldehyde, acetaldehyde, crotonaldehyde or with any other aliphatic aldehyde as desired. Although our invention in its preferable form comprises the manufacture and use as an accelerator of vulcanizaa;

tion of the heptaldehyde derivative of butylidene-dianilide, the manufacture and use of any other material wherein heptaldehyde is used either in the preparation of the Schiifs base or the final aldehyde derivative prepared therefrom is within the scope of our present invention.

The materials hereinbefore mentioned may be used in the preparation of vulcanized rub her as are shown by the following examples.

If 0.5 parts of the heptaldehyde derivative of butylidene-dianilide be added in the usual manner to a mix previously broken down on the mixing mills and comprising 100 parts of pale crepe rubber, 5 parts of zinc oxide and 3.5 parts of sulfur and the mixture vulcanized in a press for approximately fortyfive minutes at the temperature given by 40 pounds of steam pressure per square inch, a

vulcanized product is obtained which is found l '1.

to posses a modulus of elasticity at 300% elongation of 244, at 500% elongation of 635, at 700% elongation of 2735, a load at break of 4425 pounds per square inch and an ultimate elongation of 7 ill) Other compounds of the type prepared as I disclosed in the present application have likewise shown valuable vulcanization accelerating characteristlcs when incorporated into a rubber composition. For example, a vulcan- J15 ized rubber product has been obtained by employing in place of the accelerator shown in the above rubber composition, 0.5 parts of the material obtained by the reaction of heptaldehyde upon the reaction product of 2 mols of aniline with 1 mol of acetaldehyde. In a like manner, 0.5 parts of the heptaldehyde reaction product of croton-aldehyde-aniline may be employed in place of the accelerator specified in the above rubber mixture. In

this case, it is found that a vulcanized rubber product possessing desirable commercial charlnch.

The accelerators herein inentioned and prepared according to the manner as set forth may likewise be employed in the manufacture of other vulcanized products than the one described. Other rubber mixtures adaptable to the use of the accelerators of the type herein described are apparent to those skilled in the art of rubber compounding.

It is to be understood that the examples given herein are illustrative only and are not limitative of our invention. The present application is a division of our copending application, Serial No. 100,684, filed April 8, 1926.

'What we claim is:

1. The process of vulcanizing rubber which comprises heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of an alk lidene-di-aryl-amine.

2. The process of vulcanizing rubber which comprises heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of an alkylidene-di-anilide.

3. The process of vulcanizing rubber which comprises heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of butylidene-dianilide.

l. The process of vulcanizing rubber which comprises heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of an alkylidene-diaryl-amine, wherein said alkylidene-diaryl-amine product is prepared from an aliphatic aldehyde containing less than five carbon atoms and an aromatic amine.

5. The process of vulcanizing rubber which comprises heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of allrylidene-dianilide, wherein said alkylidene-dianilide is prepared from an aliphatic aldehyde containing less than five carbon atoms and aniline.

6. The process of vulcanizing rubber which comprises heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde deriative of a reaction product of substantially two molecular proportions of a primary aromatic amine and substantially one molecular proportion of an aliphatic aldehyde.

7. The process of vulcanizing rubber which comprises heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of a reaction product of substantially two molecu lar proportions of aniline and substantially one molecular proportion of butyric aldehyde.

8. The vulcanized rubber product prepared by heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of an alkylidene-diaryl-amine.

9. The vulcanized rubber product prepared by heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of an alkylidene-dianilide.

10. The vulcanized rubber product prepared by heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of buty lidene-dianilide.

11. The vulcanized rubber product prepared by heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of an alkylidene-diaryl-amine, wherein said alkylidene-diaryl-amine product is prepared from an aliphatic aldehyde containing less than five carbon atoms and an aromatic amine.

12. The vulcanized rubber product prepared by heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of an alkylidene-dianilide, wherein said alkylidenedianilide is prepared from an aliphatic aldehyde containing less than five carbon atoms and aniline.

13. The vulcanized rubber product prepared by heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of a reaction product of substantially two molecular proportions of a primary aromatic amine and substantially one molecular proportion of an aliphatic aldehyde.

14. The vulcanized rubber product prepared by heating rubber and sulfur in the presence of a vulcanization accelerator comprising a heptaldehyde derivative of a reaction product of substantially two molecular proportions of aniline and substantially one molecular proportion of butyric aldehyde.

In testimony whereof we hereunto affix our signatures.

CLAYTON OLIN NORTH. WINFIELD SCOTT. 

